Parser.y.pp 52.2 KB
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--								-*-haskell-*-
-- ---------------------------------------------------------------------------
-- (c) The University of Glasgow 1997-2003
---
-- The GHC grammar.
--
-- Author(s): Simon Marlow, Sven Panne 1997, 1998, 1999
-- ---------------------------------------------------------------------------

{
module Parser ( parseModule, parseStmt, parseIdentifier, parseIface ) where

#define INCLUDE #include 
INCLUDE "HsVersions.h"

import HsSyn
import RdrHsSyn
import HscTypes		( ModIface, IsBootInterface, DeprecTxt )
import Lexer
import RdrName
import TysWiredIn	( unitTyCon, unitDataCon, tupleTyCon, tupleCon, nilDataCon,
			  listTyCon_RDR, parrTyCon_RDR, consDataCon_RDR )
import Type		( funTyCon )
import ForeignCall	( Safety(..), CExportSpec(..), 
			  CCallConv(..), CCallTarget(..), defaultCCallConv
			)
import OccName		( UserFS, varName, dataName, tcClsName, tvName )
import DataCon		( DataCon, dataConName )
import SrcLoc		( Located(..), unLoc, getLoc, noLoc, combineSrcSpans,
			  SrcSpan, combineLocs, mkGeneralSrcSpan, srcLocFile )
import Module
import CmdLineOpts	( opt_SccProfilingOn )
import Type		( Kind, mkArrowKind, liftedTypeKind )
import BasicTypes	( Boxity(..), Fixity(..), FixityDirection(..), IPName(..),
			  NewOrData(..), Activation(..) )
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import OrdList
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import Bag		( emptyBag )
import Panic

import CStrings		( CLabelString )
import FastString
import Maybes		( orElse )
import Outputable
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import GLAEXTS
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}

{-
-----------------------------------------------------------------------------
Conflicts: 29 shift/reduce, [SDM 19/9/2002]

10 for abiguity in 'if x then y else z + 1'		[State 136]
	(shift parses as 'if x then y else (z + 1)', as per longest-parse rule)
	10 because op might be: : - ! * . `x` VARSYM CONSYM QVARSYM QCONSYM

1 for ambiguity in 'if x then y else z with ?x=3' 	[State 136]
	(shift parses as 'if x then y else (z with ?x=3)'

1 for ambiguity in 'if x then y else z :: T'		[State 136]
	(shift parses as 'if x then y else (z :: T)', as per longest-parse rule)

8 for ambiguity in 'e :: a `b` c'.  Does this mean 	[States 160,246]
	(e::a) `b` c, or 
	(e :: (a `b` c))

1 for ambiguity in 'let ?x ...'				[State 268]
	the parser can't tell whether the ?x is the lhs of a normal binding or
	an implicit binding.  Fortunately resolving as shift gives it the only
	sensible meaning, namely the lhs of an implicit binding.

1 for ambiguity in '{-# RULES "name" [ ... #-}		[State 332]
	we don't know whether the '[' starts the activation or not: it
  	might be the start of the declaration with the activation being
	empty.  --SDM 1/4/2002

1 for ambiguity in '{-# RULES "name" forall = ... #-}' 	[State 394]
	since 'forall' is a valid variable name, we don't know whether
	to treat a forall on the input as the beginning of a quantifier
	or the beginning of the rule itself.  Resolving to shift means
	it's always treated as a quantifier, hence the above is disallowed.
	This saves explicitly defining a grammar for the rule lhs that
	doesn't include 'forall'.

6 for conflicts between `fdecl' and `fdeclDEPRECATED', 	[States 384,385]
  	which are resolved correctly, and moreover, 
  	should go away when `fdeclDEPRECATED' is removed.

-- ---------------------------------------------------------------------------
-- Adding location info

This is done in a stylised way using the three macros below, L0, L1
and LL.  Each of these macros can be thought of as having type

   L0, L1, LL :: a -> Located a

They each add a SrcSpan to their argument.

   L0	adds 'noSrcSpan', used for empty productions

   L1   for a production with a single token on the lhs.  Grabs the SrcSpan
	from that token.

   LL   for a production with >1 token on the lhs.  Makes up a SrcSpan from
        the first and last tokens.

These suffice for the majority of cases.  However, we must be
especially careful with empty productions: LL won't work if the first
or last token on the lhs can represent an empty span.  In these cases,
we have to calculate the span using more of the tokens from the lhs, eg.

	| 'newtype' tycl_hdr '=' newconstr deriving
		{ L (comb3 $1 $4 $5)
		    (mkTyData NewType (unLoc $2) [$4] (unLoc $5)) }

We provide comb3 and comb4 functions which are useful in such cases.

Be careful: there's no checking that you actually got this right, the
only symptom will be that the SrcSpans of your syntax will be
incorrect.

/*
 * We must expand these macros *before* running Happy, which is why this file is
 * Parser.y.pp rather than just Parser.y - we run the C pre-processor first.
 */
#define L0   L noSrcSpan
#define L1   sL (getLoc $1)
#define LL   sL (comb2 $1 $>)

-- -----------------------------------------------------------------------------

-}

%token
 '_'            { L _ ITunderscore }		-- Haskell keywords
 'as' 		{ L _ ITas }
 'case' 	{ L _ ITcase }  	
 'class' 	{ L _ ITclass } 
 'data' 	{ L _ ITdata } 
 'default' 	{ L _ ITdefault }
 'deriving' 	{ L _ ITderiving }
 'do' 		{ L _ ITdo }
 'else' 	{ L _ ITelse }
 'hiding' 	{ L _ IThiding }
 'if' 		{ L _ ITif }
 'import' 	{ L _ ITimport }
 'in' 		{ L _ ITin }
 'infix' 	{ L _ ITinfix }
 'infixl' 	{ L _ ITinfixl }
 'infixr' 	{ L _ ITinfixr }
 'instance' 	{ L _ ITinstance }
 'let' 		{ L _ ITlet }
 'module' 	{ L _ ITmodule }
 'newtype' 	{ L _ ITnewtype }
 'of' 		{ L _ ITof }
 'qualified' 	{ L _ ITqualified }
 'then' 	{ L _ ITthen }
 'type' 	{ L _ ITtype }
 'where' 	{ L _ ITwhere }
 '_scc_'	{ L _ ITscc }	      -- ToDo: remove

 'forall'	{ L _ ITforall }			-- GHC extension keywords
 'foreign'	{ L _ ITforeign }
 'export'	{ L _ ITexport }
 'label'	{ L _ ITlabel } 
 'dynamic'	{ L _ ITdynamic }
 'safe'		{ L _ ITsafe }
 'threadsafe'	{ L _ ITthreadsafe }
 'unsafe'	{ L _ ITunsafe }
 'mdo'		{ L _ ITmdo }
 'stdcall'      { L _ ITstdcallconv }
 'ccall'        { L _ ITccallconv }
 'dotnet'       { L _ ITdotnet }
 'proc'		{ L _ ITproc }		-- for arrow notation extension
 'rec'		{ L _ ITrec }		-- for arrow notation extension

 '{-# SPECIALISE'  { L _ ITspecialise_prag }
 '{-# SOURCE'	   { L _ ITsource_prag }
 '{-# INLINE'      { L _ ITinline_prag }
 '{-# NOINLINE'    { L _ ITnoinline_prag }
 '{-# RULES'	   { L _ ITrules_prag }
 '{-# CORE'        { L _ ITcore_prag }              -- hdaume: annotated core
 '{-# SCC'	   { L _ ITscc_prag }
 '{-# DEPRECATED'  { L _ ITdeprecated_prag }
 '{-# UNPACK'      { L _ ITunpack_prag }
 '#-}'		   { L _ ITclose_prag }

 '..'		{ L _ ITdotdot }  			-- reserved symbols
 ':'		{ L _ ITcolon }
 '::'		{ L _ ITdcolon }
 '='		{ L _ ITequal }
 '\\'		{ L _ ITlam }
 '|'		{ L _ ITvbar }
 '<-'		{ L _ ITlarrow }
 '->'		{ L _ ITrarrow }
 '@'		{ L _ ITat }
 '~'		{ L _ ITtilde }
 '=>'		{ L _ ITdarrow }
 '-'		{ L _ ITminus }
 '!'		{ L _ ITbang }
 '*'		{ L _ ITstar }
 '-<'		{ L _ ITlarrowtail }		-- for arrow notation
 '>-'		{ L _ ITrarrowtail }		-- for arrow notation
 '-<<'		{ L _ ITLarrowtail }		-- for arrow notation
 '>>-'		{ L _ ITRarrowtail }		-- for arrow notation
 '.'		{ L _ ITdot }

 '{'		{ L _ ITocurly } 			-- special symbols
 '}'		{ L _ ITccurly }
 '{|'           { L _ ITocurlybar }
 '|}'           { L _ ITccurlybar }
 vocurly	{ L _ ITvocurly } -- virtual open curly (from layout)
 vccurly	{ L _ ITvccurly } -- virtual close curly (from layout)
 '['		{ L _ ITobrack }
 ']'		{ L _ ITcbrack }
 '[:'		{ L _ ITopabrack }
 ':]'		{ L _ ITcpabrack }
 '('		{ L _ IToparen }
 ')'		{ L _ ITcparen }
 '(#'		{ L _ IToubxparen }
 '#)'		{ L _ ITcubxparen }
 '(|'		{ L _ IToparenbar }
 '|)'		{ L _ ITcparenbar }
 ';'		{ L _ ITsemi }
 ','		{ L _ ITcomma }
 '`'		{ L _ ITbackquote }

 VARID   	{ L _ (ITvarid    _) }		-- identifiers
 CONID   	{ L _ (ITconid    _) }
 VARSYM  	{ L _ (ITvarsym   _) }
 CONSYM  	{ L _ (ITconsym   _) }
 QVARID  	{ L _ (ITqvarid   _) }
 QCONID  	{ L _ (ITqconid   _) }
 QVARSYM 	{ L _ (ITqvarsym  _) }
 QCONSYM 	{ L _ (ITqconsym  _) }

 IPDUPVARID   	{ L _ (ITdupipvarid   _) }		-- GHC extension
 IPSPLITVARID  	{ L _ (ITsplitipvarid _) }		-- GHC extension

 CHAR		{ L _ (ITchar     _) }
 STRING		{ L _ (ITstring   _) }
 INTEGER	{ L _ (ITinteger  _) }
 RATIONAL	{ L _ (ITrational _) }
		    
 PRIMCHAR	{ L _ (ITprimchar   _) }
 PRIMSTRING	{ L _ (ITprimstring _) }
 PRIMINTEGER	{ L _ (ITprimint    _) }
 PRIMFLOAT	{ L _ (ITprimfloat  _) }
 PRIMDOUBLE	{ L _ (ITprimdouble _) }
 		    
-- Template Haskell 
'[|'            { L _ ITopenExpQuote  }       
'[p|'           { L _ ITopenPatQuote  }      
'[t|'           { L _ ITopenTypQuote  }      
'[d|'           { L _ ITopenDecQuote  }      
'|]'            { L _ ITcloseQuote    }
TH_ID_SPLICE    { L _ (ITidEscape _)  }     -- $x
'$('	        { L _ ITparenEscape   }     -- $( exp )
TH_VAR_QUOTE	{ L _ ITvarQuote      }     -- 'x
TH_TY_QUOTE	{ L _ ITtyQuote       }      -- ''T

%monad { P } { >>= } { return }
%lexer { lexer } { L _ ITeof }
%name parseModule module
%name parseStmt   maybe_stmt
%name parseIdentifier  identifier
%name parseIface iface
%tokentype { Located Token }
%%

-----------------------------------------------------------------------------
-- Module Header

-- The place for module deprecation is really too restrictive, but if it
-- was allowed at its natural place just before 'module', we get an ugly
-- s/r conflict with the second alternative. Another solution would be the
-- introduction of a new pragma DEPRECATED_MODULE, but this is not very nice,
-- either, and DEPRECATED is only expected to be used by people who really
-- know what they are doing. :-)

module 	:: { Located (HsModule RdrName) }
 	: 'module' modid maybemoddeprec maybeexports 'where' body 
		{% fileSrcSpan >>= \ loc ->
		   return (L loc (HsModule (Just (L (getLoc $2) 
					(mkHomeModule (unLoc $2))))
				$4 (fst $6) (snd $6) $3)) }
	| missing_module_keyword top close
		{% fileSrcSpan >>= \ loc ->
		   return (L loc (HsModule Nothing Nothing 
				(fst $2) (snd $2) Nothing)) }

missing_module_keyword :: { () }
	: {- empty -}				{% pushCurrentContext }

maybemoddeprec :: { Maybe DeprecTxt }
	: '{-# DEPRECATED' STRING '#-}' 	{ Just (getSTRING $2) }
	|  {- empty -}				{ Nothing }

body 	:: { ([LImportDecl RdrName], [LHsDecl RdrName]) }
	:  '{'            top '}'		{ $2 }
 	|      vocurly    top close		{ $2 }

top 	:: { ([LImportDecl RdrName], [LHsDecl RdrName]) }
	: importdecls				{ (reverse $1,[]) }
	| importdecls ';' cvtopdecls		{ (reverse $1,$3) }
	| cvtopdecls				{ ([],$1) }

cvtopdecls :: { [LHsDecl RdrName] }
	: topdecls				{ cvTopDecls $1 }

-----------------------------------------------------------------------------
-- Interfaces (.hi-boot files)

iface   :: { ModIface }
	: 'module' modid 'where' ifacebody  { mkBootIface (unLoc $2) $4 }

ifacebody :: { [HsDecl RdrName] }
	:  '{'            ifacedecls '}'		{ $2 }
 	|      vocurly    ifacedecls close		{ $2 }

ifacedecls :: { [HsDecl RdrName] }
	: ifacedecl ';' ifacedecls	{ $1 : $3 }
	| ';' ifacedecls		{ $2 }
	| ifacedecl			{ [$1] }
	| {- empty -}			{ [] }

ifacedecl :: { HsDecl RdrName }
	: var '::' sigtype	
                { SigD (Sig $1 $3) }
 	| 'type' syn_hdr '=' ctype	
 		{ let (tc,tvs) = $2 in TyClD (TySynonym tc tvs $4) }
	| 'data' tycl_hdr
		{ TyClD (mkTyData DataType (unLoc $2) [] Nothing) }
	| 'newtype' tycl_hdr
		{ TyClD (mkTyData NewType (unLoc $2) [] Nothing) }
	| 'class' tycl_hdr fds
		{ TyClD (mkClassDecl (unLoc $2) (unLoc $3) [] emptyBag) }

-----------------------------------------------------------------------------
-- The Export List

maybeexports :: { Maybe [LIE RdrName] }
	:  '(' exportlist ')'			{ Just $2 }
	|  {- empty -}				{ Nothing }

exportlist :: { [LIE RdrName] }
 	:  exportlist ',' export		{ $3 : $1 }
	|  exportlist ','			{ $1 }
 	|  export				{ [$1]  }
	|  {- empty -}				{ [] }

   -- No longer allow things like [] and (,,,) to be exported
   -- They are built in syntax, always available
export 	:: { LIE RdrName }
	:  qvar				{ L1 (IEVar (unLoc $1)) }
	|  oqtycon			{ L1 (IEThingAbs (unLoc $1)) }
	|  oqtycon '(' '..' ')'		{ LL (IEThingAll (unLoc $1)) }
	|  oqtycon '(' ')'		{ LL (IEThingWith (unLoc $1) []) }
	|  oqtycon '(' qcnames ')'	{ LL (IEThingWith (unLoc $1) (reverse $3)) }
	|  'module' modid		{ LL (IEModuleContents (unLoc $2)) }

qcnames :: { [RdrName] }
	:  qcnames ',' qcname			{ unLoc $3 : $1 }
	|  qcname				{ [unLoc $1]  }

qcname 	:: { Located RdrName }	-- Variable or data constructor
	:  qvar					{ $1 }
	|  gcon					{ $1 }

-----------------------------------------------------------------------------
-- Import Declarations

-- import decls can be *empty*, or even just a string of semicolons
-- whereas topdecls must contain at least one topdecl.

importdecls :: { [LImportDecl RdrName] }
	: importdecls ';' importdecl		{ $3 : $1 }
	| importdecls ';'			{ $1 }
	| importdecl				{ [ $1 ] }
	| {- empty -}				{ [] }

importdecl :: { LImportDecl RdrName }
	: 'import' maybe_src optqualified modid maybeas maybeimpspec 
		{ L (comb4 $1 $4 $5 $6) (ImportDecl $4 $2 $3 (unLoc $5) (unLoc $6)) }

maybe_src :: { IsBootInterface }
	: '{-# SOURCE' '#-}'			{ True }
	| {- empty -}				{ False }

optqualified :: { Bool }
      	: 'qualified'                           { True  }
      	| {- empty -}				{ False }

maybeas :: { Located (Maybe ModuleName) }
      	: 'as' modid                            { LL (Just (unLoc $2)) }
      	| {- empty -}				{ noLoc Nothing }

maybeimpspec :: { Located (Maybe (Bool, [LIE RdrName])) }
	: impspec				{ L1 (Just (unLoc $1)) }
	| {- empty -}				{ noLoc Nothing }

impspec :: { Located (Bool, [LIE RdrName]) }
	:  '(' exportlist ')'  			{ LL (False, reverse $2) }
	|  'hiding' '(' exportlist ')' 		{ LL (True,  reverse $3) }

-----------------------------------------------------------------------------
-- Fixity Declarations

prec 	:: { Int }
	: {- empty -}		{ 9 }
	| INTEGER		{% checkPrecP (L1 (fromInteger (getINTEGER $1))) }

infix 	:: { Located FixityDirection }
	: 'infix'				{ L1 InfixN  }
	| 'infixl'				{ L1 InfixL  }
	| 'infixr'				{ L1 InfixR }

ops   	:: { Located [Located RdrName] }
	: ops ',' op				{ LL ($3 : unLoc $1) }
	| op					{ L1 [$1] }

-----------------------------------------------------------------------------
-- Top-Level Declarations

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topdecls :: { OrdList (LHsDecl RdrName) }	-- Reversed
	: topdecls ';' topdecl		{ $1 `appOL` $3 }
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	| topdecls ';'			{ $1 }
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	| topdecl			{ $1 }
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topdecl :: { OrdList (LHsDecl RdrName) }
  	: tycl_decl			{ unitOL (L1 (TyClD (unLoc $1))) }
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	| 'instance' inst_type where
		{ let (binds,sigs) = cvBindsAndSigs (unLoc $3)
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		  in unitOL (L (comb3 $1 $2 $3) (InstD (InstDecl $2 binds sigs))) }
	| 'default' '(' comma_types0 ')'	{ unitOL (LL $ DefD (DefaultDecl $3)) }
	| 'foreign' fdecl			{ unitOL (LL (unLoc $2)) }
	| '{-# DEPRECATED' deprecations '#-}'	{ $2 }
	| '{-# RULES' rules '#-}'		{ $2 }
	| '$(' exp ')'				{ unitOL (LL $ SpliceD (SpliceDecl $2)) }
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      	| decl					{ unLoc $1 }

tycl_decl :: { LTyClDecl RdrName }
 	: 'type' syn_hdr '=' ctype	
		-- Note ctype, not sigtype.
		-- We allow an explicit for-all but we don't insert one
		-- in 	type Foo a = (b,b)
		-- Instead we just say b is out of scope
 		{ LL $ let (tc,tvs) = $2 in TySynonym tc tvs $4 }

	| 'data' tycl_hdr constrs deriving
		{ L (comb4 $1 $2 $3 $4)
		    (mkTyData DataType (unLoc $2) (reverse (unLoc $3)) (unLoc $4)) }

	| 'newtype' tycl_hdr '=' newconstr deriving
		{ L (comb3 $1 $4 $5)
		    (mkTyData NewType (unLoc $2) [$4] (unLoc $5)) }

	| 'class' tycl_hdr fds where
		{ let 
			(binds,sigs) = cvBindsAndSigs (unLoc $4)
		  in
	 	  L (comb4 $1 $2 $3 $4) (mkClassDecl (unLoc $2) (unLoc $3) sigs 
					  binds) }

syn_hdr :: { (Located RdrName, [LHsTyVarBndr RdrName]) }
		-- We don't retain the syntax of an infix
		-- type synonym declaration. Oh well.
	: tycon tv_bndrs		{ ($1, $2) }
	| tv_bndr tyconop tv_bndr 	{ ($2, [$1,$3]) }

-- tycl_hdr parses the header of a type or class decl,
-- which takes the form
--	T a b
-- 	Eq a => T a
--	(Eq a, Ord b) => T a b
-- Rather a lot of inlining here, else we get reduce/reduce errors
tycl_hdr :: { Located (LHsContext RdrName, Located RdrName, [LHsTyVarBndr RdrName]) }
	: context '=>' type		{% checkTyClHdr $1 $3 >>= return.LL }
	| type				{% checkTyClHdr (noLoc []) $1 >>= return.L1 }

-----------------------------------------------------------------------------
-- Nested declarations

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decls 	:: { Located (OrdList (LHsDecl RdrName)) }	-- Reversed
	: decls ';' decl		{ LL (unLoc $1 `appOL` unLoc $3) }
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	| decls ';'			{ LL (unLoc $1) }
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	| decl				{ $1 }
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	| {- empty -}			{ noLoc nilOL }
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decllist :: { Located (OrdList (LHsDecl RdrName)) }	-- Reversed
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	: '{'            decls '}'	{ LL (unLoc $2) }
	|     vocurly    decls close	{ $2 }

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where 	:: { Located (OrdList (LHsDecl RdrName)) }	-- Reversed
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				-- No implicit parameters
	: 'where' decllist		{ LL (unLoc $2) }
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	| {- empty -}			{ noLoc nilOL }
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binds 	::  { Located [HsBindGroup RdrName] } 	-- May have implicit parameters
	: decllist			{ L1 [cvBindGroup (unLoc $1)] }
	| '{'            dbinds '}'	{ LL [HsIPBinds (unLoc $2)] }
	|     vocurly    dbinds close	{ L (getLoc $2) [HsIPBinds (unLoc $2)] }

wherebinds :: { Located [HsBindGroup RdrName] }	-- May have implicit parameters
	: 'where' binds			{ LL (unLoc $2) }
	| {- empty -}			{ noLoc [] }


-----------------------------------------------------------------------------
-- Transformation Rules

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rules	:: { OrdList (LHsDecl RdrName) }	-- Reversed
	:  rules ';' rule			{ $1 `snocOL` $3 }
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        |  rules ';'				{ $1 }
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        |  rule					{ unitOL $1 }
	|  {- empty -}				{ nilOL }
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rule  	:: { LHsDecl RdrName }
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	: STRING activation rule_forall infixexp '=' exp
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	     { LL $ RuleD (HsRule (getSTRING $1) $2 $3 $4 $6) }
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activation :: { Activation }           -- Omitted means AlwaysActive
        : {- empty -}                           { AlwaysActive }
        | explicit_activation                   { $1 }

inverse_activation :: { Activation }   -- Omitted means NeverActive
        : {- empty -}                           { NeverActive }
        | explicit_activation                   { $1 }

explicit_activation :: { Activation }  -- In brackets
        : '[' INTEGER ']'		{ ActiveAfter  (fromInteger (getINTEGER $2)) }
        | '[' '~' INTEGER ']'		{ ActiveBefore (fromInteger (getINTEGER $3)) }

rule_forall :: { [RuleBndr RdrName] }
	: 'forall' rule_var_list '.'            { $2 }
        | {- empty -}				{ [] }

rule_var_list :: { [RuleBndr RdrName] }
        : rule_var				{ [$1] }
        | rule_var rule_var_list		{ $1 : $2 }

rule_var :: { RuleBndr RdrName }
	: varid                              	{ RuleBndr $1 }
       	| '(' varid '::' ctype ')'             	{ RuleBndrSig $2 $4 }

-----------------------------------------------------------------------------
-- Deprecations (c.f. rules)

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deprecations :: { OrdList (LHsDecl RdrName) }	-- Reversed
	: deprecations ';' deprecation		{ $1 `appOL` $3 }
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	| deprecations ';' 			{ $1 }
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	| deprecation				{ $1 }
	| {- empty -}				{ nilOL }
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-- SUP: TEMPORARY HACK, not checking for `module Foo'
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deprecation :: { OrdList (LHsDecl RdrName) }
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	: depreclist STRING
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		{ toOL [ LL $ DeprecD (Deprecation n (getSTRING $2)) 
		       | n <- unLoc $1 ] }
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-----------------------------------------------------------------------------
-- Foreign import and export declarations

-- for the time being, the following accepts foreign declarations conforming
-- to the FFI Addendum, Version 1.0 as well as pre-standard declarations
--
-- * a flag indicates whether pre-standard declarations have been used and
--   triggers a deprecation warning further down the road
--
-- NB: The first two rules could be combined into one by replacing `safety1'
--     with `safety'.  However, the combined rule conflicts with the
--     DEPRECATED rules.
--
fdecl :: { LHsDecl RdrName }
fdecl : 'import' callconv safety1 fspec
		{% mkImport $2 $3 (unLoc $4) >>= return.LL }
      | 'import' callconv         fspec		
		{% do { d <- mkImport $2 (PlaySafe False) (unLoc $3);
			return (LL d) } }
      | 'export' callconv fspec
		{% mkExport $2 (unLoc $3) >>= return.LL }
        -- the following syntax is DEPRECATED
      | fdecl1DEPRECATED			{ L1 (ForD (unLoc $1)) }
      | fdecl2DEPRECATED			{ L1 (unLoc $1) }

fdecl1DEPRECATED :: { LForeignDecl RdrName }
fdecl1DEPRECATED 
  ----------- DEPRECATED label decls ------------
  : 'label' ext_name varid '::' sigtype
    { LL $ ForeignImport $3 $5 (CImport defaultCCallConv (PlaySafe False) nilFS nilFS 
				   (CLabel ($2 `orElse` mkExtName (unLoc $3)))) True }

  ----------- DEPRECATED ccall/stdcall decls ------------
  --
  -- NB: This business with the case expression below may seem overly
  --	 complicated, but it is necessary to avoid some conflicts.

    -- DEPRECATED variant #1: lack of a calling convention specification
    --			      (import) 
  | 'import' {-no callconv-} ext_name safety varid_no_unsafe '::' sigtype
    { let
	target = StaticTarget ($2 `orElse` mkExtName (unLoc $4))
      in
      LL $ ForeignImport $4 $6 (CImport defaultCCallConv $3 nilFS nilFS 
				   (CFunction target)) True }

    -- DEPRECATED variant #2: external name consists of two separate strings
    --			      (module name and function name) (import)
  | 'import' callconv STRING STRING safety varid_no_unsafe '::' sigtype
    {% case $2 of
         DNCall      -> parseError (comb2 $1 $>) "Illegal format of .NET foreign import"
	 CCall cconv -> return $
           let
	     imp = CFunction (StaticTarget (getSTRING $4))
	   in
	   LL $ ForeignImport $6 $8 (CImport cconv $5 nilFS nilFS imp) True }

    -- DEPRECATED variant #3: `unsafe' after entity
  | 'import' callconv STRING 'unsafe' varid_no_unsafe '::' sigtype
    {% case $2 of
         DNCall      -> parseError (comb2 $1 $>) "Illegal format of .NET foreign import"
	 CCall cconv -> return $
           let
	     imp = CFunction (StaticTarget (getSTRING $3))
	   in
	   LL $ ForeignImport $5 $7 (CImport cconv PlayRisky nilFS nilFS imp) True }

    -- DEPRECATED variant #4: use of the special identifier `dynamic' without
    --			      an explicit calling convention (import)
  | 'import' {-no callconv-} 'dynamic' safety varid_no_unsafe '::' sigtype
    { LL $ ForeignImport $4 $6 (CImport defaultCCallConv $3 nilFS nilFS 
				   (CFunction DynamicTarget)) True }

    -- DEPRECATED variant #5: use of the special identifier `dynamic' (import)
  | 'import' callconv 'dynamic' safety varid_no_unsafe '::' sigtype
    {% case $2 of
         DNCall      -> parseError (comb2 $1 $>) "Illegal format of .NET foreign import"
	 CCall cconv -> return $
	   LL $ ForeignImport $5 $7 (CImport cconv $4 nilFS nilFS 
					(CFunction DynamicTarget)) True }

    -- DEPRECATED variant #6: lack of a calling convention specification
    --			      (export) 
  | 'export' {-no callconv-} ext_name varid '::' sigtype
    { LL $ ForeignExport $3 $5 (CExport (CExportStatic ($2 `orElse` mkExtName (unLoc $3))
				   defaultCCallConv)) True }

    -- DEPRECATED variant #7: external name consists of two separate strings
    --			      (module name and function name) (export)
  | 'export' callconv STRING STRING varid '::' sigtype
    {% case $2 of
         DNCall      -> parseError (comb2 $1 $>) "Illegal format of .NET foreign import"
	 CCall cconv -> return $
           LL $ ForeignExport $5 $7 
			 (CExport (CExportStatic (getSTRING $4) cconv)) True }

    -- DEPRECATED variant #8: use of the special identifier `dynamic' without
    --			      an explicit calling convention (export)
  | 'export' {-no callconv-} 'dynamic' varid '::' sigtype
    { LL $ ForeignImport $3 $5 (CImport defaultCCallConv (PlaySafe False) nilFS nilFS 
				   CWrapper) True }

    -- DEPRECATED variant #9: use of the special identifier `dynamic' (export)
  | 'export' callconv 'dynamic' varid '::' sigtype
    {% case $2 of
         DNCall      -> parseError (comb2 $1 $>) "Illegal format of .NET foreign import"
	 CCall cconv -> return $
	   LL $ ForeignImport $4 $6 
		 (CImport cconv (PlaySafe False) nilFS nilFS CWrapper) True }

  ----------- DEPRECATED .NET decls ------------
  -- NB: removed the .NET call declaration, as it is entirely subsumed
  --     by the new standard FFI declarations

fdecl2DEPRECATED :: { LHsDecl RdrName }
fdecl2DEPRECATED 
  : 'import' 'dotnet' 'type' ext_name tycon { LL $ TyClD (ForeignType $5 $4 DNType) }
    -- left this one unchanged for the moment as type imports are not
    -- covered currently by the FFI standard -=chak


callconv :: { CallConv }
	  : 'stdcall'			{ CCall  StdCallConv }
	  | 'ccall'			{ CCall  CCallConv   }
	  | 'dotnet'			{ DNCall	     }

safety :: { Safety }
	: 'unsafe'			{ PlayRisky }
	| 'safe'			{ PlaySafe False }
	| 'threadsafe'			{ PlaySafe True  }
	| {- empty -}			{ PlaySafe False }

safety1 :: { Safety }
	: 'unsafe'			{ PlayRisky }
	| 'safe'			{ PlaySafe  False }
	| 'threadsafe'			{ PlaySafe  True }
	  -- only needed to avoid conflicts with the DEPRECATED rules

fspec :: { Located (Located FastString, Located RdrName, LHsType RdrName) }
       : STRING var '::' sigtype      { LL (L (getLoc $1) (getSTRING $1), $2, $4) }
       |        var '::' sigtype      { LL (noLoc nilFS, $1, $3) }
         -- if the entity string is missing, it defaults to the empty string;
         -- the meaning of an empty entity string depends on the calling
         -- convention

-- DEPRECATED syntax
ext_name :: { Maybe CLabelString }
	: STRING		{ Just (getSTRING $1) }
	| STRING STRING		{ Just (getSTRING $2) }	-- Ignore "module name" for now
	| {- empty -}           { Nothing }


-----------------------------------------------------------------------------
-- Type signatures

opt_sig :: { Maybe (LHsType RdrName) }
	: {- empty -}			{ Nothing }
	| '::' sigtype			{ Just $2 }

opt_asig :: { Maybe (LHsType RdrName) }
	: {- empty -}			{ Nothing }
	| '::' atype			{ Just $2 }

sigtypes :: { [LHsType RdrName] }
	: sigtype			{ [ $1 ] }
	| sigtypes ',' sigtype		{ $3 : $1 }

sigtype :: { LHsType RdrName }
	: ctype				{ L1 (mkImplicitHsForAllTy (noLoc []) $1) }
	-- Wrap an Implicit forall if there isn't one there already

sig_vars :: { Located [Located RdrName] }
	 : sig_vars ',' var		{ LL ($3 : unLoc $1) }
	 | var				{ L1 [$1] }

-----------------------------------------------------------------------------
-- Types

-- A ctype is a for-all type
ctype	:: { LHsType RdrName }
	: 'forall' tv_bndrs '.' ctype	{ LL $ mkExplicitHsForAllTy $2 (noLoc []) $4 }
	| context '=>' type		{ LL $ mkImplicitHsForAllTy   $1 $3 }
	-- A type of form (context => type) is an *implicit* HsForAllTy
	| type				{ $1 }

-- We parse a context as a btype so that we don't get reduce/reduce
-- errors in ctype.  The basic problem is that
--	(Eq a, Ord a)
-- looks so much like a tuple type.  We can't tell until we find the =>
context :: { LHsContext RdrName }
	: btype 			{% checkContext $1 }

type :: { LHsType RdrName }
	: ipvar '::' gentype		{ LL (HsPredTy (LL $ HsIParam (unLoc $1) $3)) }
	| gentype			{ $1 }

gentype :: { LHsType RdrName }
        : btype                         { $1 }
        | btype qtyconop gentype        { LL $ HsOpTy $1 $2 $3 }
        | btype  '`' tyvar '`' gentype  { LL $ HsOpTy $1 $3 $5 }
	| btype '->' gentype		{ LL $ HsFunTy $1 $3 }

btype :: { LHsType RdrName }
	: btype atype			{ LL $ HsAppTy $1 $2 }
	| atype				{ $1 }

atype :: { LHsType RdrName }
	: gtycon			{ L1 (HsTyVar (unLoc $1)) }
	| tyvar				{ L1 (HsTyVar (unLoc $1)) }
	| '(' type ',' comma_types1 ')'	{ LL $ HsTupleTy Boxed  ($2:$4) }
	| '(#' comma_types1 '#)'	{ LL $ HsTupleTy Unboxed $2     }
	| '[' type ']'			{ LL $ HsListTy  $2 }
	| '[:' type ':]'		{ LL $ HsPArrTy  $2 }
	| '(' ctype ')'		        { LL $ HsParTy   $2 }
	| '(' ctype '::' kind ')'	{ LL $ HsKindSig $2 $4 }
-- Generics
        | INTEGER                       { L1 (HsNumTy (getINTEGER $1)) }

-- An inst_type is what occurs in the head of an instance decl
--	e.g.  (Foo a, Gaz b) => Wibble a b
-- It's kept as a single type, with a MonoDictTy at the right
-- hand corner, for convenience.
inst_type :: { LHsType RdrName }
	: ctype				{% checkInstType $1 }

comma_types0  :: { [LHsType RdrName] }
	: comma_types1			{ $1 }
	| {- empty -}			{ [] }

comma_types1	:: { [LHsType RdrName] }
	: type				{ [$1] }
	| type  ',' comma_types1	{ $1 : $3 }

tv_bndrs :: { [LHsTyVarBndr RdrName] }
	 : tv_bndr tv_bndrs		{ $1 : $2 }
	 | {- empty -}			{ [] }

tv_bndr :: { LHsTyVarBndr RdrName }
	: tyvar				{ L1 (UserTyVar (unLoc $1)) }
	| '(' tyvar '::' kind ')'	{ LL (KindedTyVar (unLoc $2) $4) }

fds :: { Located [Located ([RdrName], [RdrName])] }
	: {- empty -}			{ noLoc [] }
	| '|' fds1			{ LL (reverse (unLoc $2)) }

fds1 :: { Located [Located ([RdrName], [RdrName])] }
	: fds1 ',' fd			{ LL ($3 : unLoc $1) }
	| fd				{ L1 [$1] }

fd :: { Located ([RdrName], [RdrName]) }
	: varids0 '->' varids0		{ L (comb3 $1 $2 $3)
					   (reverse (unLoc $1), reverse (unLoc $3)) }

varids0	:: { Located [RdrName] }
	: {- empty -}			{ noLoc [] }
	| varids0 tyvar			{ LL (unLoc $2 : unLoc $1) }

-----------------------------------------------------------------------------
-- Kinds

kind	:: { Kind }
	: akind			{ $1 }
	| akind '->' kind	{ mkArrowKind $1 $3 }

akind	:: { Kind }
	: '*'			{ liftedTypeKind }
	| '(' kind ')'		{ $2 }


-----------------------------------------------------------------------------
-- Datatype declarations

newconstr :: { LConDecl RdrName }
	: conid atype	{ LL $ ConDecl $1 [] (noLoc []) 
				(PrefixCon [(unbangedType $2)]) }
	| conid '{' var '::' ctype '}'
			{ LL $ ConDecl $1 [] (noLoc []) 
				  (RecCon [($3, (unbangedType $5))]) }

constrs :: { Located [LConDecl RdrName] }
        : {- empty; a GHC extension -}  { noLoc [] }
        | '=' constrs1                  { LL (unLoc $2) }

constrs1 :: { Located [LConDecl RdrName] }
	: constrs1 '|' constr		{ LL ($3 : unLoc $1) }
	| constr			{ L1 [$1] }

constr :: { LConDecl RdrName }
	: forall context '=>' constr_stuff	
		{ let (con,details) = unLoc $4 in 
		  LL (ConDecl con (unLoc $1) $2 details) }
	| forall constr_stuff
		{ let (con,details) = unLoc $2 in 
		  LL (ConDecl con (unLoc $1) (noLoc []) details) }

forall :: { Located [LHsTyVarBndr RdrName] }
	: 'forall' tv_bndrs '.'		{ LL $2 }
	| {- empty -}			{ noLoc [] }

constr_stuff :: { Located (Located RdrName, HsConDetails RdrName (LBangType RdrName)) }
	: btype				{% mkPrefixCon $1 [] >>= return.LL }
	| btype bang_atype satypes	{% do { r <- mkPrefixCon $1 ($2 : unLoc $3);
					        return (L (comb3 $1 $2 $3) r) } }
	| oqtycon '{' '}' 		{% mkRecCon $1 [] >>= return.LL }
	| oqtycon '{' fielddecls '}' 	{% mkRecCon $1 $3 >>= return.LL }
	| sbtype conop sbtype		{ LL ($2, InfixCon $1 $3) }

bang_atype :: { LBangType RdrName }
	: strict_mark atype		{ LL (BangType (unLoc $1) $2) }

satypes	:: { Located [LBangType RdrName] }
	: atype satypes			{ LL (unbangedType $1 : unLoc $2) }
	| bang_atype satypes		{ LL ($1 : unLoc $2) }
	| {- empty -}			{ noLoc [] }

sbtype :: { LBangType RdrName }
	: btype				{ unbangedType $1 }
	| strict_mark atype		{ LL (BangType (unLoc $1) $2) }

fielddecls :: { [([Located RdrName], LBangType RdrName)] }
	: fielddecl ',' fielddecls	{ unLoc $1 : $3 }
	| fielddecl			{ [unLoc $1] }

fielddecl :: { Located ([Located RdrName], LBangType RdrName) }
	: sig_vars '::' stype		{ LL (reverse (unLoc $1), $3) }

stype :: { LBangType RdrName }
	: ctype				{ unbangedType $1 }
	| strict_mark atype		{ LL (BangType (unLoc $1) $2) }

strict_mark :: { Located HsBang }
	: '!'				{ L1 HsStrict }
	| '{-# UNPACK' '#-}' '!'	{ LL HsUnbox }

deriving :: { Located (Maybe (LHsContext RdrName)) }
	: {- empty -}			{ noLoc Nothing }
	| 'deriving' context		{ LL (Just $2) }
             -- Glasgow extension: allow partial 
             -- applications in derivings

-----------------------------------------------------------------------------
-- Value definitions

{- There's an awkward overlap with a type signature.  Consider
	f :: Int -> Int = ...rhs...
   Then we can't tell whether it's a type signature or a value
   definition with a result signature until we see the '='.
   So we have to inline enough to postpone reductions until we know.
-}

{-
  ATTENTION: Dirty Hackery Ahead! If the second alternative of vars is var
  instead of qvar, we get another shift/reduce-conflict. Consider the
  following programs:
  
     { (^^) :: Int->Int ; }          Type signature; only var allowed

     { (^^) :: Int->Int = ... ; }    Value defn with result signature;
				     qvar allowed (because of instance decls)
  
  We can't tell whether to reduce var to qvar until after we've read the signatures.
-}

924
decl 	:: { Located (OrdList (LHsDecl RdrName)) }
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	: sigdecl			{ $1 }
	| infixexp opt_sig rhs		{% do { r <- checkValDef $1 $2 (unLoc $3);
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						return (LL $ unitOL (LL $ ValD r)) } }
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rhs	:: { Located (GRHSs RdrName) }
	: '=' exp wherebinds	{ L (comb3 $1 $2 $3) $ GRHSs (unguardedRHS $2) (unLoc $3) placeHolderType }
	| gdrhs	wherebinds	{ LL $ GRHSs (reverse (unLoc $1)) (unLoc $2) placeHolderType }

gdrhs :: { Located [LGRHS RdrName] }
	: gdrhs gdrh		{ LL ($2 : unLoc $1) }
	| gdrh			{ L1 [$1] }

gdrh :: { LGRHS RdrName }
	: '|' quals '=' exp  	{ LL $ GRHS (reverse (L (getLoc $4) (ResultStmt $4) : 
							unLoc $2)) }

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sigdecl :: { Located (OrdList (LHsDecl RdrName)) }
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	: infixexp '::' sigtype
				{% do s <- checkValSig $1 $3; 
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				      return (LL $ unitOL (LL $ SigD s)) }
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		-- See the above notes for why we need infixexp here
	| var ',' sig_vars '::' sigtype	
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				{ LL $ toOL [ LL $ SigD (Sig n $5) | n <- $1 : unLoc $3 ] }
	| infix prec ops	{ LL $ toOL [ LL $ SigD (FixSig (FixitySig n (Fixity $2 (unLoc $1))))
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					     | n <- unLoc $3 ] }
	| '{-# INLINE'   activation qvar '#-}'	      
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				{ LL $ unitOL (LL $ SigD (InlineSig True  $3 $2)) }
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	| '{-# NOINLINE' inverse_activation qvar '#-}' 
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				{ LL $ unitOL (LL $ SigD (InlineSig False $3 $2)) }
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	| '{-# SPECIALISE' qvar '::' sigtypes '#-}'
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			 	{ LL $ toOL [ LL $ SigD (SpecSig $2 t)
					    | t <- $4] }
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	| '{-# SPECIALISE' 'instance' inst_type '#-}'
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				{ LL $ unitOL (LL $ SigD (SpecInstSig $3)) }
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-----------------------------------------------------------------------------
-- Expressions

exp   :: { LHsExpr RdrName }
	: infixexp '::' sigtype		{ LL $ ExprWithTySig $1 $3 }
	| fexp '-<' exp		{ LL $ HsArrApp $1 $3 placeHolderType HsFirstOrderApp True }
	| fexp '>-' exp		{ LL $ HsArrApp $3 $1 placeHolderType HsFirstOrderApp False }
	| fexp '-<<' exp	{ LL $ HsArrApp $1 $3 placeHolderType HsHigherOrderApp True }
	| fexp '>>-' exp	{ LL $ HsArrApp $3 $1 placeHolderType HsHigherOrderApp False}
	| infixexp			{ $1 }

infixexp :: { LHsExpr RdrName }
	: exp10				{ $1 }
	| infixexp qop exp10		{ LL (OpApp $1 $2 (panic "fixity") $3) }

exp10 :: { LHsExpr RdrName }
	: '\\' aexp aexps opt_asig '->' exp	
			{% checkPatterns ($2 : reverse $3) >>= \ ps -> 
			   return (LL $ HsLam (LL $ Match ps $4
					    (GRHSs (unguardedRHS $6) []
							placeHolderType))) }
  	| 'let' binds 'in' exp			{ LL $ HsLet (unLoc $2) $4 }
	| 'if' exp 'then' exp 'else' exp	{ LL $ HsIf $2 $4 $6 }
   	| 'case' exp 'of' altslist		{ LL $ HsCase $2 (unLoc $4) }
	| '-' fexp				{ LL $ mkHsNegApp $2 }

  	| 'do' stmtlist			{% let loc = comb2 $1 $2 in
					   checkDo loc (unLoc $2)  >>= \ stmts ->
					   return (L loc (mkHsDo DoExpr stmts)) }
  	| 'mdo' stmtlist		{% let loc = comb2 $1 $2 in
					   checkMDo loc (unLoc $2)  >>= \ stmts ->
					   return (L loc (mkHsDo MDoExpr stmts)) }

        | scc_annot exp		    		{ LL $ if opt_SccProfilingOn
							then HsSCC (unLoc $1) $2
							else HsPar $2 }

	| 'proc' aexp '->' exp	
			{% checkPattern $2 >>= \ p -> 
			   return (LL $ HsProc p (LL $ HsCmdTop $4 [] 
						   placeHolderType undefined)) }